During the winter, many of us living in Northern climes have shorter days and less exposure to sunlight meaning a decreased ability to manufacture our own Vitamin D. Vitamin D plays an important role in our well-being; essential for healthy bone growth, neuromuscular and immune functions, as well as reduction of inflammations and prevention of respiratory infections.
Vitamin D is synthesized in our bodies when skin is exposed to UV rays from sunlight, though age, the amount of time spent in the sun, melanin levels in the skin and sunscreen application can affect absorption levels. Vitamin D can also be obtained by consuming certain foods rich in the vitamin, though the natural options are limited to oily fish, beef liver, eggs and fortunately mushrooms. There are also fortified foods that can be consumed such as milk, cereal, orange juice, yogurt and margarine as well as dietary supplements. Mushrooms are the only produce that contain vitamin D naturally and thus should become of every diet.
The following is an abbreviated list comparing the amount of Vitamin D in food we consume (measured in International Units (IU))demonstrating the important levels mushrooms contain. Fruits and vegetable are not featured in this chart since none contain vitamin D and though fortified, ready-to-eat cereals do contain vitamin D, they are high in sugar and low in nutritional value and hence were not included. The entire list can be viewed on the USDA website.
|IU VALUE PER 100 GRAM|
|Portobello, exposed to UV light||524|
|Tuna fish, canned, in oil||269|
|Pork spare ribs||104|
|Bacon, reduced sodium||42|
|Milk, whole, fortified||420|
|American cheese, fortified||301|
*extracted from the USDA National Nutrient Database for Standard Reference release 27
Vitamin D promotes the absorption of calcium essential for healthy bone growth preventing them from becoming brittle, thin and/or misshapen. Lack of Vitamin D can cause rickets in children and osteoporosis in adults, two conditions that can be prevented. Additionally, studies suggest that Vitamin D may affect cancer risk. Though still inconclusive, there is strong evidence that vitamin D has protective effects on certain cancers including breast and prostate, though the most promising results came from research involving patients with colon cancer. More recently, there has been evidence that Vitamin D could play a role in the prevention and treatment of Type 1 and 2 diabetes as well as MS and hypertension. Lastly, a study conducted at Cambridge University concluded that increased Vitamin D in the body increased the preventive effect against influenza by boosting the bodies’ immune levels. NB Excessive levels of vitamin D can also be harmful to the body.
People at greater risk of Vitamin D deficiency include growing children, darker skinned individuals, overweight persons and the elderly. Children need calcium for bone development and tend to be protected against direct exposure to sunlight, dark skin contains more melanin which is less effective in producing vitamin D from sunlight, obese individuals sequester vitamin D in fat preventing its release into other parts of the body and the elderly have skin that doesn’t synthesize efficiently and are inclined to stay indoors more often.
Vitamin D deficiency can be reversed by consuming foods rich in this nutrient. The Dietary Guidelines for Americans put forth by the federal government recommend that nutrients should be obtained from foods. Although dietary supplements are valuable, vitamins obtained from natural foods have added health benefits that can help the body function properly and boost the immune system. Mushrooms that naturally produce vitamin D should become part of every diet.
Sources: Journal of Virology2008 – review on The Epidemiology of influenza, National Institutes of Health, Office of Dietary Supplements, Vitamin D Facts sheet for professionals, Facts sheet for consumers, USDA National Nutrient Database for Standard Reference release 27, Office of Disease Prevention and Health Promotion, The Dietary Guidelines for Americans.
Terrafunga does not offer medical advice. Readers should seek medical advice from a licensed physician or other qualified health care professional and not rely on information they may gather from secondary sources such as the internet.